Numerous decaffeination techniques are known in the art. One widely practiced decaffeination method is disclosed in U.S. Pat. No. 2,309,092 to Berry et al. Green coffee beans are moistened and subsequently extracted with a caffeine-deficient green coffee extract, with the extraction typically taking place in a countercurrent extraction battery Caffeine-laden extract withdrawn from the extraction battery is then decaffeinated by contact with a caffeine solvent. While the method of Berry et al. is quite effective, it is only applicable to the decaffeination of green coffee beans and is not suitable for the decaffeination of extracts of roasted coffee.
The art has generally continued to progress along lines of decaffeination of green extracts. Relatively little progress has been made in technology looking toward the direct decaffeination of the extract of roasted and ground coffee. To be sure, certain patents like that to Adler et al., U.S. Pat. No. 2,933,395 issued Apr. 9, 1960, have offered to the art workers the approach of decaffeinating the extract of roasted and ground coffee; but such arts have not materially advanced until recently to the point of providing a brew quality equal to or exceeding that recoverable by decaffeination of green beans.
Thus, techniques are known for decaffeinating roasted coffee extracts, but the methods are not without certain drawbacks. Belgian Patent Disclosure No. 865,488 of Bolt et al. describes a process in which roasted coffee extract is first decaffeinated with the solvent, the solvent is then contacted with water to transfer the caffeine and unavoidably some non-caffeine solubles, the decaffeinated solvent is returned to the coffee extract and subsequently stripped therefrom; and the caffeine is crystallized from the water phase, which is then discarded. The water phase unavoidably contains an amount of noncaffeine solubles which would contribute important flavor notes but which are instead discarded. The particular flavor notes which are lost with the discarded water phase are the "body" notes which contribute to the overall balance of coffee extract flavor. Without these body notes, the coffee extract and the soluble coffee made therefrom are typically characterized as weak and thin.
A similar decaffeination method is disclosed in U.S. Pat. No. 4,409,253 to Morrison et al. The improvement is said to be in recycling the water phase from which the caffeine has been crystallized back to the incoming caffeinecontaining extract. It appears that the water phase cannot be combined with the decaffeinated extract because of the substantial amounts of caffeine remaining in the water after crystallization. This inefficient recycling of the water phase, with the corresponding increase in the amount of caffeine to be removed, would appear to increase the volume of extract to be decaffeinated, inflating operating costs.
Accordingly, it is an object of the present invention to provide an efficient method for decaffeinating aqueous roasted coffee extracts.
Another object of the invention is to provide a method of decaffeinating aqueous roasted coffee extracts which minimizes the amount of flavor notes lost during decaffeination.
Such improvements as have been noted in the production of decaffeinated extract produced from roasted and ground coffee leave much to be desired from the standpoint of flavor. It would be desirable to provide a decaffeination process which uses roasted and ground coffee, instead of green; is relatively applicable to current processing techniques; and yields a product that can match or exceed the quality extracts derived from decaffeinated green beans. The present invention relates to just such a product.